1. Field of the Invention
The present disclosure relates to molded case circuit breaker and particularly, to the molded case circuit breaker (abbreviated as MCCB hereinafter) having a fault indicating relay.
2. Background of the Invention
A MCCB is an electric power device which includes a trip mechanism and a switching mechanism and is used to switch and protect a relatively low voltage circuit of hundreds of volts by detecting an overcurrent equivalent to about 120 percent of a rated current, an instantaneous current (i.e., a very large current to be broken instantaneously) corresponding to a few times to tens of times the rated current, flowing in an electric power circuit (abbreviated as circuit hereinafter), or a ground fault current occurring as at least one pole of current, among three poles, leaks to a ground. Namely, when the overcurrent or the instantaneous current to be broken instantaneously flows or the ground fault current flows, the trip mechanism triggers the switching mechanism to move to a circuit breaking (so-called trip) position, and the switching mechanism, triggered by the trip mechanism, is driven to a trip position in which a movable contact is automatically separated from a corresponding fixed contact, or driven to an ON position in which a movable contact of the circuit is brought into contact with a corresponding fixed contact according to user's manipulation of a switching operation handle to close the circuit.
If such an MCCB, when performing a trip operation (namely, automatic circuit breaking) due to an overcurrent, an instantaneous current, or a ground fault current, may indicate the accident cause of the overcurrent, the instantaneous current, or the ground fault current, the accident cause may be promptly removed and an electric power may be supplied again to an electric load to perform re-operation, shortening a time taken from a power failure to a normal load operation.
Thus, as illustrated in FIGS. 1 and 2, a related art MCCB 100 includes an electronic trip unit 30 detecting an overcurrent, an instantaneous current, or a ground fault current and triggering a switching mechanism to move to a circuit breaking (or tripping) position. The electronic trip unit 30 includes a fault type indication light emitting diode (abbreviated as LED hereinafter) 31 indicating a type of an accident current.
However, according to the method of indicating a type of an accident current through the fault type indication LED 31 provided in the electronic trip unit 30 of the related art MCCB 100 illustrated in FIGS. 1 and 2, a user should check or view the fault type indication LED 31 to check an accident cause, causing user inconvenience, and in particular, in a case in which the MCCB 100 is installed within an outer case with a door, such as a power dividing box or a power distributing cabinet, such inconvenience is aggravated.
In addition, in order to transmit an fault type indication command signal from the electronic trip unit 30 of the MCCB 100 to a front indication operation panel of an enclosure of the power dividing box or the power distributing cabinet or to a remote monitoring system, a transceiver unit for communication needs to be provided in the electronic trip unit 30 and complicated transmission and reception lines based on a communication scheme needs to be installed, increasing manufacturing cost of the MCCB 100, and installation of the transmission and reception lines causes an operation of a considerable amount of time and an installation space for a user, which is, thus, burdensome.